Moment Magnitude is the measure of total energy released
by an earthquake. Moment magnitude is the measurement and
term generally prefered by scientists and seismologists to
the Richter scale because moment magnitude is more precise.

Moment Magnitude is not based on
instrumental recordings of a quake, but on the area of the
fault that ruptured in the quake. This means that the moment
magnitude describes something physical about an earthquake.
Moment Magnitude is calculated in part by multiplying the
area of the fault's rupture surface by the distance the earth
moves along the fault